Pneumatic cushion

ABSTRACT

A pneumatic cushion having preinflated sealed cells with pressure compensators for distributing air between cells in response to loads placed thereon, the pneumatic cushion having a mid sheet with top and bottom surfaces, a top layer of preinflated sealed cells attached to the top surface of the mid sheet, a bottom layer of preinflated sealed cells attached to the bottom surface of the mid sheet, and pressure compensators affixed to the mid sheet and in communication with each top and bottom cell whereby upon uneven loading of the sealed cells air is stepwise transferred by the pressure compensators from a cell of high pressure on a first layer to a cell on a second layer and then to another cell on the first and so on to smooth out the uneven pressure.

The invention relates to pneumatic cushions particularly adaptable foruse in connection wigh chairs or beds. More specifically the pneumaticcushion of this invention has sealed air chabmers and pressurecompensator means for localized surface deflection.

Persons who must spend great amounts of time lying in bed or sitting inchairs among other problems are prone to experience pressure sores. Muchattention has been given to this problem with many and varied solutions.Even so, it has been generally agreed that concentrated pressure areascaused by the patient's prominences result in reduced circulation insuch body areas thus producing patient discomfort in the form ofpressure sores.

Solutions to this specific problem, i.e. pressure sores are of manydifferent types such as convoluted foam pads of various thicknesses, gelpads, static, and cyclically pressurized air cushions and watermattresses. All of the foregoing appear to have certain outstandingcharacteristics and have received a share of the commewrcial market.Even so, none of the pressure cushion units have met with universal andoverwhelming success.

OBJECTS AND SUMMARY OF THE INVENTION

In view of the foregoing it is an object of this invention to provide asealed pneumatic cushion having pressure distribution means.

It is another object of this invention to provide a sealed pneumaticcushion having means to reduce and equalize pressure at stress pointsproduced by prominences of the patient.

It is yet another object of this invention to provide a pneumaticcushion wherein the cushion comprises a top layer of inflated sealedcells and a bottom layer of inflated sealed cells said cells beinginterconnected by pressure compensators which will transfer air from atop to a bottom cell.

It is a still further object to provide the pneumatic cushion as setforth in the immediately preceding objects and wherein under localdeflection of an upper or bottom cell a distribution of pressureradiates outwardly from such deflection.

It is a further object of this invention to provide a pneumatic cushionof the type set forth in the preceding objects and wherein individualair leaks in some of the cells will not render the cushion inoperative.

The above objects are achieved by the preferred embodiment of thisinvention wherein the pneumatic cushion comprises a top layer ofinflated and sealed cells and a bottom layer of inflated and sealedcells said upper cells being interconnected with the bottom cells bypressure compensators which transfer air from upper cells to bottomcells to transfer pressure from a high pressure point outwardly togradually reduce said high pressure.

IN THE DRAWINGS

FIG. 1 is a top plan view of the basic pneumatic cushion which as shownis a chair cushion suitable for use on a wheelchair,

FIG. 2 is a cross sectional view taken along line A--A of FIG. 1illustrating the relative positioning of top and bottom cells and thepressure compensators located therein,

FIG. 3 is a cross sectional view taken along line B--B of FIG. 1 tofurther show the symmetrical relationship of top and bottom cells andcooperating pressure compensators, and

FIG. 4 shows three constructions of the pressure compensator namely;bellows compensator, dome compensator and diaphragm compensator,

FIG. 5 is a sectional perspective view of the pneumatic cushion innon-use condition,

FIG. 6 is a sectional perspective view of the cushion as shown in FIG. 5with a patient resting on the top cells and the bottom cells beingpositioned on a suitable base of a chair or mattress,

FIG. 7 is a cross sectional view of the pneumatic cushion with theprofile of a seated patient projected thereon illustrating thedisplacement of the pressure compensators under a bony prominence, and

FIG. 8 shows the pneumatic cushion of this invention when enlarged tofit on a bed.

DETAILED DESCRIPTION

The pneumatic cushion covered by this invention is illustrated in planin FIG. 1 and sectional and elevational condition in FIGS. 2-8. Thepneumatic cushion has a plurality of preinflated sealed top cells and aplurality of preinflated sealed bottom cells. These cells are providedwith pressure compensators for distributing air between the cells inresponse to uneven loads placed thereon.

More particularly, as shown in FIGS. 1-7, the pneumatic cushion 10comprises a top layer consisting of preinflated sealed cells 12 ofrectangular configuration and a bottom layer consisting of preinflatedsealed cells 14 also of rectangular configuration. It should be notedthat the basic cell whether top or bottom is of the same size andconfiguration except for edge cell portions.

The top layer of cells 12 is attached by heat sealing to a mid layersheet 16 on which is formed a plurality of pressure compensators 24. Topcells 12 are formed from a top layer sheet 18 and are symmetricallyarranged as clearly shown in FIG. 1. The bottom layer of cells 14comprises a plurality of rectangular inflated and sealed bottom cells 14formed from a bottom layer sheet 20. Said bottom cells 14 are heatsealed onto the underside of mid layer sheet 16. It is readily apparentthat the mid layer sheet 16 may comprise on assembly of an upper sheet16a and a lower sheet 16b secured together. See FIG. 7.

As previously set forth, the top cells 12 and the bottom cells 14 arerectangular in configuration and of the same size. Thus the specificarrangement and relationship of top to bottom cells is provided whereinthe top and bottom cells are medially offset both in the horizontal andvertical direction as shown in FIG. 1 whereby a given full top cell 12will cover the contiguous corners of four separate bottom cells 14. Thisarrangement also applies to edge portions of the top and bottom layersof cells wherein a full cell is not formed.

The above arrangement is quite important to the proper functioning ofthe pressure compensation system of this invention. More specifically, aplurality of pressure compensators 24 are formed in the mid layer sheet16. These pressure compensators may be diaphragms or bellows or domes ofelastic material which are flexible so that they will flex in thedirection of least pressure between the top and bottom cells whenarranged as set forth earlier. In other words the pressure ocmpensators24 are positioned so that they coincide with the corner portions of thecells, both top and bottom. This concept is clearly shown by FIGS. 2 and3 combined with FIG. 1. For example, referring to FIGS. 1-3, top cell12A covers the contiguous corners of bottom cells 14A, 14B, 14C and 14D.In FIGS. 2 and 3 the pressure compensators 24 are shown in slightlyoffset condition. This has been done for the sake of clarity. Actuallywhen there is no load the compensators will be in a collapsed conditionand almost flush with the mid layer sheet 16. FIG. 4 shows theconfigurations of the compensators. The compensators in general havebeen identified by the numeral 24. More specifically, in FIG. 4 the topbroken away section illustrates bellows type compensator 24A while themid broken away section shows dome type compensator 24B and the lowerbroken away section shows diaphragm compensator 24C which is made ofelastic material.

In order to describe the operation or the pneumatic cushion 10 referenceis made to FIGS. 5, 6 and 7 wherein there is shown a base 30 such as achair seat on which is positioned the pneumatic cushion 10 of thisinvention. A patient is seated on the top side of the cushion and has aprofile as shown in shaded manner in FIG. 7. The profile includes a bonyprominence 32 which causes the pressure in top cell 34 to increasebeyond that experienced in adjacent top layer cells 36 and 38. Withoutfurther action there would be additional and undersirable pressure onprominence 32. This additional pressure causes pressure compensators 40and 42 to expand into bottom cells 44 and 46 respectively therebyrelieving the effective pressure in top cell 34. The action iscontinuous because when compensator 42 moves down into bottom cell 46increased pressure is created therein causing compensator 48 to moveupwardly into top cell 38. In fact four compensators will move upwardlyinto the four contiguous corners of adjacent top cells. This sequencewas explained earlier. Thus it might be said that the pressurecompensation is rapid because it expands into many cells in a radiatingfashion. Such redistribution of pressure greatly aids in adjustingpressure in top cell 34 into which the prominence extends.

It will thus be noted that all cells both top and bottom are alwaysindependently sealed whereby movement of the pressure compensators intocells whether top or bottom produces pressure differences adapted tosomewhat equalize and reduce the pressure at the patients prominences asthey are positioned on the cushion.

FIG. 8 shows the pneumatic cushion 10 of this invention positioned on abed base 80 in no load condition with the pressure compensators 24 inthe deflated condition. The broken away and phantom portion shows themanner in which the pressure compensators 24 actively cooperate with topand bottom cells.

With regard to materils from which the cushion may be made the field isalmost endless. The sheets forming the cells and the mid layer sheetshould be made of a heat sealable material which is readily formable.The material thickness should be sufficient to provide the requisitestrength and durability. When the pressure compensators are shaped forelastic deformation obviously the mid-layer must be elastic in nature.

What is claimed is:
 1. A pneumatic cushion having preinflated sealedcells with pressure compensators for distributing air between cells inresponse to loads placed thereon, said pneumatic cushion comprising:(1)a mid sheet having top and bottom surfaces, (2) a top layer ofpreinflated sealed cells attached to the top surface of the mid sheet,(3) a bottom layer of preinflated sealed cells attached to the bottomsurface of the mid sheet, and (4) pressure compensating means affixed tothe mid sheet and in communication with each top and bottom cell wherebyupon uneven loading of the sealed cells air is stepwise transferred bysaid pressure compensating means from a cell of high pressure on a toplayer to a cell on a bottom layer and then to another cell on the saidtop and so on to smooth out the uneven pressure.
 2. The invention as setforth in claim 1 and wherein the top preinflated cells and the bottompreinflated cells are arranged so that a top cell overlaps at least twobottom cells and each bottom cell overlaps at least two top cells, thepressure compensating means being in communication with successive topand bottom cells to smooth out the uneven pressure.
 3. The invention asset forth in claim 2 and wherein the pressure compensating meanscomprises a plurality of pressure compensators attached to the midsheet, said pressure compensators being in communication with each topcell and the bottom cell it overlaps.
 4. The invention as set forth inclaim 3 and wherein the pressure compensators are flexible bellows whichtransfer air from one cell to another.
 5. The invention as set forth inclaim 3 and wherein the pressure compensators are elastic hollow memberswhich transfer air from one cell to another.
 6. A pneumatic cushionhaving preinflated sealed cells with pressure compensators fordistributing air between cells in response to loads placed thereon, saidpneumatic cushion comprising:(1) a top layer of preinflated sealedcells, (2) a bottom layer of preinflated sealed cells attached to thetop layer so that the cells of both layers are exposed, top and bottom,(3) said top layer comprising a mid layer sheet having a plurality ofrectangular inflated and sealed top cells formed from a top layer sheetattached thereto, said top cells being symmetrically arrayed on the midlayer sheet, (4) said bottom layer of cells comprising a plurality ofrectangular inflated and sealed bottom cells formed from a bottom layersheet attached to the mid layer sheet and on the opposite side from therectangular top cells having longitudinal and width-wise sides saidbottom cells being of identical configuration to the top cells andsymmetrically arrayed whereby they are medially offset with respect toboth the longitudinal and widthwise sides of the top cells so that a topcell will cover the contiguous corners of four separate bottom cells,and (5) pressure compensating means affixed to the mid layer sheet andin communication with each top and bottom cell whereby upon unevenloading of the cushion cells air is transferred from cell to cell toreduce such uneven loading of the cells.
 7. The invention as set forthin claim 6 and wherein the pressure ocmpensating means comprises aplurality of bellows like members attached to the the mid layer sheetand in communication with both the top and the bottom cells.
 8. Theinvention as set forth in claim 6 and wherein each complete top cell hasfour pressure compensators cooperating with the corner portions of thefour bottom cells it overlies.
 9. A pneumatic cushion having preinflatedsealed cells with air compensators for distributing pressure betweencells in response to loads placed thereon,s aid pneumatic cushioncomprising:(1) a mid-layer sheet assembly comprising an upper and alower sheet secured together, (2) a top layer of preinflated sealedcells attached to the upper sheet, (3) a bottom layer of preinflatedsealed cells attached to the lower sheet so that the cells of bothlayers are exposed, top and bottom, (4) said top layer comprising themid layer top sheet having a plurality of rectangular inflated andsealed top cells formed from a top layer sheet attached thereto, saidtop cells being symmetrically arrayed on the mid layer sheet, (5) saidbottom layer of cells comprising a plurality of rectangular inflated andsealed bottom cells formed from a bottom layer sheet attached to the midlayer lower sheet and on the opposite side from the rectangular topcells having longitudinal and widthwise sides said bottom cells being ofidentical configuration to the top cells and symmetrically arrayedwhereby they are medially offset with respect to both the longitudinaland widthwise sides of the top cells so that a top cell will cover thecontiguous corners of four separate bottom cells, and (6) pressurecompensating means affixed to the mid layer sheet assembly and incommunication with each top and bottom cell whereby upon uneven loadingof the sealed cells, air is transferred from cell to cell to reduce suchuneven loading of the cells.